Mayor Julián Castro ceremoniously plugged an electric vehicle into the city's new charging station at the downtown library Monday, one of six built by the city through a grant from the U.S. Department of Energy.

The stations, which cost a total of $10,000, are part of San Antonio's ongoing “progress toward becoming New Energy City USA,” Castro said, thus helping wean the country off foreign oil and keep the city in attainment with federal air quality standards.

The charging station, in front of a parking space on the first floor of the library's parking garage, is an unobtrusive silver obelisk, smaller than the sign pointing it out. An oversized white plug pulls out to meet the electric car, in this case a Chevy Volt from the city's fleet.

There's a tiny beep, and Castro steps back.

“There. That's it. We know it's charging from this little green light,” he says, pointing to the dash of the car.

The car will get a full charge in just four hours from the “level one” charger.

Castro said he hopes the budding EV infrastructure in town will be convenient for those who already have an electric car — about 50 local people had such cars as of September, said Bill Barker of the city's Office of Environmental Policy — and encourage those who might be thinking about it.

The private sector also has begun building stations. KB Home is offering them as a feature in some new homes, and CPS Energy is partnering with businesses around the city to put in another 100 stations.

That effort is on track, said Julia Jones, a CPS research manager in charge of the utility's electric vehicle unit, and the utility expects to make an announcement next month about all the locations.

“They'll be well-dispersed throughout the city,” she said.

They are part of a DOE research project, Jones said. CPS will collect data on charging patterns, behavior and economics for the department.

“We're learning a lot already,” she said. “This is really new for everyone.”

The annual market for hybrid electric and plug-in electric vehicles will grow to 2.9 million vehicles by 2017, according to Pike Research, a clean technology market research and consulting firm, in a report released last quarter.

“Increasing fuel costs, government purchase incentives, increasing fuel-economy standards, and increased vehicle availability will benefit both segments of electric vehicles to varying degrees,” according to the report's authors.

The $10,000 spent on the six stations in San Antonio was part of a larger, $12.9 million energy efficiency and conservation block grant from the DOE. The city also has spent money from that grant, which was part of the Obama administration's stimulus program, on the B-cycle bike-share program, rebates for retrofitting homes to increase their energy efficiency, tree planting and other initiatives.

The DOE is working to maintain a nationwide database of charging stations, and hosts a website where EV drivers can search for nearby stations, get directions and even contact them by phone.